Energy storage is a fundamental problem or limitation that results in waste of energy at one time and shortage of energy at other times. This waste or shortage occurs because electricity generated by conventional sources such as thermal power plants are not always consumed as the electricity is produced. Thermal power plants need to run at their peak load at all times to maximize efficiency in power generation. If the peak output is sufficient to meet the peak demand, then energy is wasted during off peak hours. If the power plant output does not meet peak demand, but meets demand during off peak hours, then there is energy shortage during peak hours. If the power plant output capacity is increased to meet the peak demand, then the wastage of energy due to inefficiency increases. Lack of balance between demand and supply also lead to grid failures and power outages that cost the power infrastructure companies.